Furnace



p 2, 1939. R-H. NELSON 2,172,667

FURNACE Filed Aug. 10, 1936 4 Sheets-Sheet 1 P 2, 1939. R H. NELSON 2,172,667

FURNACE Filed Aug. 10, 1936 4 Sheets-Sheet 2 QKUAQL A Sept. 12, 1939. R H. NELSON FURNACE Filed Aug. 10, 1936 4 Sheets-Sheet 3 w A i w m m u AM YWM iii Sept. 12, 1939. R. H. NELSON FURNACE File d Aug. 10, 1936 4 Sheets-Sheet 4 F F. Fur-IF. TFFF. FFPEEP-EECCCEF-C mq jj EkFTEw:

. MEN [3 WMafc/fi 9550 Patented; Se t 12, 1939 RATENT OFFICE FURNACE Richard H. Nelson, Moline, Ill., assignor The Herman Nelson Corporation, Molina, 111., a corporation of Illinois Application August It), 1936, Serial No. 95,141

8 Claims.

This invention relates to a furnace and more particularly to an air conditioning type of furnace of the forced draft type.

The furnace of my invention is a compact unit, preferably employing oil as the combustion fuel and provided with an induction blower to create a stack draft and reduce the tendency of the gases of combustion to seep into the air flow passages surrounding the combustion chamber and ilues or ducts. The furnace of my construction also preferably embodies flues or ducts for the combustion gases which are provided with fins or ribs both inside and outside for the better transfer of heat from the combustion gases to the air flowing past the flues or ducts, and with the ribs or fins spaced more closely where the temperature difference between the gases and air is lower so as to equalize the amount of heat transferred along the length of such ducts or flues.

A further important feature of my invention is the provision of a common driving means for the fuel pump, the blower for creating a forced air draft and the induction blower for creating a stack draft, whereby a simpler and more economical form of construction is obtained. A thermostatically controlled damper is provided which is automatically closed until after the furnace has warmed up and which is automatically kept open after the motor is stopped to provide for simple convection of the air until after the furnace has cooled off.

It is therefore an important object of this invention to provide a furnace of the improved construction above described, which is simple and economical in its operation.

Other and further important objects of this invention will be apparent from the disclosures in the specification and the accompanying drawings.

This invention (in a preferred form) is illustrated in the drawings and hereinafter more fully described.

On the drawings:

Figure 1 is a longitudinal sectional view, with parts in elevation, of a furnace of my invention.

Figure 2 is a sectional view taken substantially along the line IIII of Fig. 1.

Figure 3 is a sectional view taken substantially along the line IIIIII of Fig. 1.

Figure 4 is a sectional view taken substantially along the line IVIV of Fig. 1.

Figure 5 is a sectional view taken substantially along the broken line VV of Fig. 1. 1

Figure 6 is an enlarged detail view of the damper and control arrangement.

As shown on the drawings:

The reference numeral Hi indicates generally an outer casing or housing formed of a suitable gauge of sheet metal and enclosing the various operative elements of a furnace embodying the features of my invention. Said housing l0 comprises end walls H and i2, side walls 13 and M, a bottom wall l5 and a top wall I8 from which latter wall extends a stack H for conducting the heated air to the branch ducts and thence to the registers used in heating the room, building, or the like.

The interior of said housing 10 is divided by a horizontal plate It into a lower air intake and mixing space H. The lower portion of the side wall I3 terminates at the horizontal plate l8, as at 20 (Fig. 4-), and a foraminous screen and air filter 2| is positioned therebeneath to permit the flow of air into the chamber [9. One or more blower or fan units 22 are mounted within said chamber l9 supported from the horizontal plate I8. Each of said blower units includes a blower proper 23 mounted upon a horizontal axis 24, the ends of which extend through bearing plates 25 and 26 secured to supporting members 21 and 28, respectively. The casings of said blower units 22 are opened at their ends, as at 29, to permit air to bedrawn thereinto, and the horizontal plate I8 is apertured as at 30 (Fig. 4), to permit the upward flow of air into the space thereabove.

In the space above the plate It, there is mounted a combustion chamber, indicated generally by the reference numeral 3| and comprising an elongated cylindrical fire boxhaving an outer shell 35 32 of metal and an inner refractory lining 33. At one end of said combustion chamber 3| oil' burner equipment is mounted upon the plate l8, including a draft casing 34, which extends through an opening in said end of the combustion 0 chamber. An oil supply pipe 35 leads to the oil burner, indicated generally by the reference numeral 36.

The other end of the combustion chamber 3| has a conduit 31 leading upwardly to a plurality of longitudinally extending ducts 38 arranged in two sets or banks of three ducts each. Said. ducts are flattened to present their narrow rounded lower portions 40 to. the upwardly ascending air currents and their flattened f aces M are arranged in closely spaced parallel relation to provide passages 42 therebetween. At the further end from the intake duct 31, a header box 43 (Fig. 5) extends across all of the horizontal ducts 38 to direct the flue gases issuing from the first set of ducts into the second set of iucts. From the sec nd set of ducts, the flugases passthrough a,

/ header box 44' into the housing of .an induction blower 45. and thence are'deliv'eredto a staclr v riveted or otherwise secured to the inner fiat verflue gases to the metal walls of the ducts for,

tical surfaces of' the ducts. These finsor ribs 36 serve'to absorb and transfer the heat from theradiation into the air passing'around'and outside of the ducts:

. the outside flat walls of said ducts 38, said fins or ribs taking the form of angle irons 48 or channel irons 49, depending upon their position along the length of said'dubts.

" I have found that more efhcient heat transfer can be effected if the outer fins orribs 4? have substantially a logarithmic spacing, the ribs or fins G'i being spaced more closely along, the length of the. ducts 38 where the temperature of the flue gases passing through said ducts is lower. The channel members til are therefore positioned along the ducts 38 toward the discharge ends thereof, while the angle irons 48 are positioned at the intake ends of said ducts. Thus, the amount of heat radiated by said fins or ribs M7 is largely equalized throughout the length of said ducts by virtue of the greater radiating surface area where the temperature of the,fiue gases passing through the ducts is lower.

The driving mechanism (Figs. "1 and 3) comprises a motor 50, suitably mounted within the "lower compartment l9 at one end thereof, and having a shaft 5i to which are keyed a pair of pulleys 52. One of said pulleys 52 drives a pulley 53 on the shaft 2 3 through a belt 56. A second belt 55 is trained around a pulley 56 secured on a pump shaft 51 and around a pulley 58 secured on the induction blower shaft 5Q. Said second belt 55 is driven by the other of the pulleys 52 on the motor shaft 5i. I have thus provided a common driving means for all of the moving parts in the furnace assembly.

An arrangement of dampers for the flow of air past the combustion chamber Si is provided comprising a pair of plate dampers 60 and 6! (Fig. 4) hinged at their lower edges, as at 62 and 63, respectively, from adjacent the side walls l3 and- Id. Said dampers 60 and 6t extend substantially the full length of the combustion chamber 3i and in their closed position rest with their upper edges against the outer wall of said combustion chamber. In their open position, shown in dotted lines in Fig. 4, said dampers 60 and 61 are substantially vertical and parallel to the side walls l3 and It. The dampers are of relatively light sheet metal construction and are provided with angle irons 64 and 65 which serve as counterweights to cause the dampers to fall into closed position when there is no air flow from the blowers 23. The flow of air, when the blowers 23 are operating, is sufflcient to open the dampers 60 and 66 in the absence of any means for regulating their position.

Means are provided, however, for regulating and controlling the dampers 60 and SI so that these dampers will remain closed until after the furnace has been brought up to a predetermined temperature, and also for keeping the dampers open after the motor 50 has been shut off until the temperature of the furnace has dropped below a predetermined point. Such means com- Fins or ribs ii are also secured to {prise a horizontally extending frame portion 66 (Fig.- 4) having depending from each'end thereof a. bimetal rod' 61 carrying atits free end a cam shaped plate 68. Said plates 68 are provided with a lower arcuateshaped surface 69 terminating at one end in a hooked portion l0.'

The bimetal rods 61 are so constructed that upon being heated they bend in a plane parallel to the side walls I3 and M, as best illustrated'in dotted lines in Fig. 8. The upper edges of the dampers 60 and iii, are provided with stepped recesses H and 12 of less and greater depth, re-

spectively. Normally, with the furnace cold as at tlie starting up of the furnace, the bimetal rods 67 are in vertical position and out of alignment withtnerecesses Hand ll, so that the cam plates 68 resist the opening of the dampers 60 and 6 i. The'd'arnpers therefore remain shut even after the motor 55 has been started up and the blowers 23 set in operation. However, as the furnace heats up; due to the combustion of fuel within the combustion chamber 3|, the bimetal rods 6? bend until they assume the position indicated by the letter A, (Fig. 6). In this position, the cam plates 68 are in alignment with the deeper recesses 12 and the dampers 60 and 6! are thus free to move upwardly under the force of the draft of air from the fans or blowers 23. The

, dampers thereupon assume the substantially vertical position shown in dotted lines in Fig. 4 and continue to remain open so long as the furnace is in operation.

Upon the shutting off of the motor 50, and consequently of the burnerand other operating elements of the furnace, but before the furnace has cooled down substantially, the bimetal rods "61 are in their extreme bent position indicated by the letter B (Fig. 6). In this position, the ends of the cam plates 68 overlie the edges of the recessed portions ll of said dampers 68 and 6! to prevent the dampers from falling shut. As the furnace continues to cool down, the bimetal rods 61 come to assume the position indicated by the letter A (Fig. 6), where the cam plates 68 are in align ment with the deeper recesses 12 and the dampers 60 and Eli are free to fall closed by reason of the counterweights 64 and 65. During this interval while the furnace is cooling off and the dampers are open, a natural convection of air through the furnace and the air ducts is permitted, so that the remaining sensible heat of the furnace parts is utilized in the heating of the air.

In order to provide for humidification and co ditioning of the air heated by the furnace, an evaporating pan (5 (Fig. 1) may be mounted above the header 43. Said evaporating pan is provided with a supply of hot water through a pipe 16 (Fig. 2) that is a part of the domestic hot water circulating system. The flow of hot Water from the pipe 16 into the evaporating pan 75 is controlled by means of a thermostatic humidity control valve 1'! which has a part 18 extending into the outlet ducts l 1 from the furnace. A humidifier feed line 19 leads from said valve 11 to control the flow of hot Water from said pipe 16 into the evaporating pan 15. An overflow line conducts the excess of water from said evaporating pan 15 to waste.

The electrical circuit for energizing the motor 50 includes a control box 8! (Fig. 2) from which a conduit 82 leads to the motor 50 and to a transformer primary within a housing 83.

I am aware that many changes may be made and numerous details of construction may be varied through a wide range without departing 7 from the principles of this invention, and I, therefore, do not purpose limiting the patent granted hereon otherwise than necessitated by the prior art. l

I claim as my invention:

1. In a furnace, a casing, a firebox therein, a blower for creating a forced upward draft of air around said firebox, dampers between walls of said casing and said firebox so arranged and of such light construction as to open under the pressure of said upward air draft, and bimetal means responsive to temperature conditions within said casing operating'to regulate said dampers to keep said dampers in closed position after starting said blower until the temperature is above a predetermined minimum and to keep said dampers open after said blower has ceased running until the temperature is below a predetermined'point.

2. In a furnace, a casing, a combustion chamber therein extending lengthwise thereof in spaced relation to the side walls of said casing, circuitous .ducts above said chamber and'in gas flow communication therewith, a blower mounted in said casing below said chamber for forcing air around and past said chamber and ducts, an induction fan for drawing gases of combustion through said ducts, dampers moimted in said casing capable in closed position of substantially closing the space between said chamber and casing and therefore of controlling the flow of air past said chamber, said dampers being normally held open by the pressure of such air flow, and temperature responsive means operating to hold said dampers in open or shut position under predetermined temperature conditions within said casing.

3. In a hot air furnace, an induction fan fo creating a stack draft, a blower for creating a forced flow of air to be heated and thermostatically controlled dampers adjacent the blower outlet for regulating said forced air flow to cut off said flow when the furnace temperature is below a predetermined point during the heating up stage and to permit said air flow during the cooling down stage until the temperature drops to a predetermined point.

4. In a hot air furnace, a casing, a combustion chamber disposed therein in spaced relation to said casing, a blower for forcing air upwardly around and past said combustion chamber to be indirectly heated therefrom, a damper mounted within said casing capable in closed position of cutting off substantially the entire flow of air around and past said combustion chamber, said damper being of sufficiently light construction and so arranged as to be normally held open by the force of the upward movement of air caused by said blower, and means responsive to the temperature of the air beyond said combustion chamber for holding said damper closed against said air force when said temperature is below a predetermined point in the heating up stage and for holding said damper open until said temperature drops below a predetermined point during the cooling down stage when said blower is not operating.

5. In a hot air furnace, heat exchange means, blower means for forcing air to be heated into heat exchange relationship therewith, damper means between the blower means and heat exchange means, said damper being so constructed and arranged as to be capable of being held open by the flow of said air caused by said blower means, and means responsive to the temperature of the air surrounding said heat exchange means for holding said damper means closed during the operation of said blower means until said temperature reaches a predetermined point in the heating up stage and for holding said damper means open until said temperature drops below a predetermined point after saidblower means has been deenergized.

6. In a hot air furnace, a combustion chamber, means for supplying fuel thereto, a heat exchange unit for receiving the gases of combustion from said chamber, an induction fan for drawing 25 said gases through said unit, a blower for forcing air past and around said chamber and unit. damper means adjacent said chamber for controlling the flow of air past said chamber and unit, and thermostatic means responsive to the temperature of the air around said heat exchange unit for holding said damper means open during the \cooling down stage when said fuel supply induction fan and blower are not operating until said temperature drops below a preas determined point, thereby permitting heating by convection during a portion of said cooling down stage.

'7- In a hot air furnace, a rectangularly shaped casing, a cylindrical combustion chamber shell extending from one end substantially to the other end of said casing and spaced from the side walls thereof to provide air passages, and damper plates extending between said side walls and shell to control said air passages, said plates in closed 45 position substantially shutting off all flow of air past said shell.

8. In a hot air furnace, a rectangularly shaped casing, a cylindrical combustion chamber shell extending from one end substantially to the other so end of said casing and spaced from the side walls thereof to provide air p'assages, a blower for forcing air through said passages, and damper plates extending between said side walls and shell to control said air passages, said plates in closed position substantially shutting 03 all flow of air past said shell but being so arranged and of such light construction as to be moved to open position by the force of the air flow caused by said blower.

RICHARD H. NELSON. 

